If you are looking to make yourself a Vodka Red Bull, it is as simple as making yourself a high ball.
You will need the following ingredients:
1 Can Red Bull
Fill a high ball glass with ice, then mix in desired amount of alcohol. If you want a single Vodka Red Bull, mix in 1.5oz vodka, if you want a double 3oz of Vodka should be added.
Next, slowly pour in your can of red bull, if it doesn't all fit, either add more Red Bull as you drink your drink, or save it to mix a second beverage.